Punch press having ram with stripping means

ABSTRACT

A punch press has a frame receptive of a punch and stripper assembly and a die, and has a ram which includes a number of fluid-pressure biased pistons which act through force transmitting means on the stripper.

United States Patent James J. Pancook Tonawanda, N.Y. 802,098

Feb. 25, 1969 Mar. 2, 1971 Houdaille Industries, Inc. Buffalo, N.Y.

Inventor Appl. No. Filed Patented Assignee PUNCH PRESS HAVING RAM WITHSTRIPPING MEANS 9 Claims, 1 Drawing Fig.

U.S. Cl 83/137 Int. Cl. B26d 7/18 Field of Search 83/ 1 37 56]References Cited UNITED STATES PATENTS 2,586,695 2/1952 Mueller 83/1372,642,138 6/1953 Macewka.... 83/137 3,107,567 10/1963 Lindner 83/137X3,119,292 1/1964 Schmid 83/137X Primary Examiner-William S. LawsonAttorneyHil1, Sherman, Meroni, Gross and Simpson ABSTRACT: A punch presshas a frame receptive of a punch and stripper assembly and a die, andhas a ram which includes a number of fluid-pressure biased pistons whichact through force transmitting means on the stripper.

PUNCH PRESS HAVING RAM WITH STRIPPING MEANS BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to structureemployed in a heavyduty punch press, and more specifically to such apress having a ram wherein fluid-pressure-biased pistons serve tocontrol or operate stripping means for stripping a workpiece from apunch.

2. Prior Art Punching machines as known in the past, particularly thoseable to punch a substantial size hole in a workpiece of substantialthickness have relied on various mechanisms for stripping the workpiecefrom the punch. To some degree, such stripping mechanism is tailored tofit the job to be done, due consideration being given to punch size andthe workpiece thickness. However, when interchangeability of tooling isprovided in a punch press wherein standardized tools are provided thathave a wide variety of punch size and that are capable of acting on awide variety of material thicknesses, the stripping means have onoccasion been found to be of inadequate strength, or have been found tobe so rigid that they may even aid deforming the workpiece whendeformation is not desired.

SUMMARY OF THE INVENTION The punch press of the present invention usesin the ram an annular piston within which is disposed a further numberofindependently operable pistons for acting through a number oftransmitting means so located as to cooperate with tooling having avariation in envelope size.

Accordingly, it is an object of the present invention to provide meansby which fluid power may be used to strip a workpiece from a punch.

Another object of the present invention is to provide a punch pressespecially adapted and arranged to strip a wide variety of workpiecethickness from a wide variety of punch size.

Many other advantages, novel features and additional objects of thepresent invention will become manifest to those versed in the art uponmaking reference to the detailed description and the accompanying sheetof drawings in which a preferred structural embodiment incorporating theprinciples of the present invention is shown by way of illustrativeexample.

ON THE DRAWINGS The single FIG. is a vertical cross-sectional view,partly in elevation, of a fragmentary portion of a punch press providedin accordance with the principles of the present invention.

AS SHOWN ON THE DRAWINGS The principles of this invention areparticularly useful when embodied in a punch press or a punching machinesuch as is fragmentarily illustrated in the drawing, generally indicatedby the numeral 10. The punch press 10 includes a frame 11 having a pairof spaced arms including an upper arm 12 and a lower arm 13, areciprocably driven ram 14 located at the upper arm 12, and verticallystationary means 15 on the frame 11 for guiding and driving reciprocablepunch and stripper means generally indicated at 16. The punch andstripper means 16 coacts with a die 17 which is supported on the lowerarm 13.

The ram 14 includes a driving portion 18 and a lower section 19 whichresembles an inverted cup. Within the lower section 19, there is secureda stem 20 which extends into the interior of the lower section 19 whereit has a cylindrical enlargement 21 spaced from an inner wall 22 of thelower section 19 to define an annular chamber 23 within which there isslidably disposed and guided a fluid-pressure biased piston 24. Fluidpressure is admitted through a port 25 and communicates with the chamber23. On application of fluid pressure to the chamber 23, the piston 24 isbiased in a downward direction to a position limitedby a ram plate 26which is secured to the enlarged portion 21 of the stem 20. The ramplate 26 has a T-head 27 integral therewith for detachably forming acoupling or connection with the punch and stripper assembly 16. The ramplate 26 has a first series of transmitting means 28 in the form oftrapped plungers which have a head or snap ring that is received in acounterbore in the ram plate 26 by which such plungers 28 are trapped.For all practical purposes, the plungers 28 have an upper end that issubstantially flush with the top surface of the ram plate 26 so that theannular piston 24 can engage either the top surface ofthe ram plate 26or the upper ends of the trapped plungers or transmitting means 28.

When pressure is applied to the chamber 23, it in effect serves as aspring urging the piston 24 downwardly for acting through thetransmitting means 28 and thus onto a number of transfer pins 29 whichform part of the stripping member that is a part of the tooling carriedin the punch press. Thus, a stripping force is made available fortransfer to a stripping member. 4

The details of thepunch, die and stripper, which form a set, do not forman essential part of the punch press of this invention, and may vary agood deal. To that end, particularly where smaller tooling is employed,the stripper pins 29 may be located somewhat closer to the center, suchas for engaging a second series of transmitting means or transfer plugs30. The transmitting means 30 is substantially the same as thetransmitting means 28 but is actually independently driven and used. Tothat end, the ram assembly 14 includes a further pair of independentlymovable fluid-pressure biased pistons 31, 32 which are slidably disposedin a pair of bores 33, 34 which are provided in the enlarged portion 21of the stem 20. Each of the pistons 24, 31,32 has a sliding seal so thatthe end thereof that acts on one ofthe transmitting means 28, 30 is alow pressure end, whereas the opposite end is the fluid-pressurized orhigh-pressure end. To that end, the bores 33, 34 communicate with apassage 35 which leads to the chamber 23.

The piston 24 has a somewhat larger effective working area than eitherof the pistons 31, 32 while the pistons 31, 32 are here shown as beingof the same size and disposed a uniform distance from the center of theram 14. This structure enables the ram assembly 14 to be used with otherpunch and stripper assemblies 16 having a scaled-down dimension whereinthe transfer pins 29 would be disposed in alignment with thetransmitting means 30..

The vertically stationary means 15 on the frame 11 may comprise a turretwhich is locked in a selected position with the proper tooling inalignment with the ram 14, or it may constitute guide meansin a singlestation press. When a worki piece is admitted between the die 17 and apunch tip 36, the ram assembly 14 is actuated which positively anddirectly drives the punch tip 36 through the workpiece into the die 17.Before the punch tip 36 enters such die, a stripper plate 37 engages theupper surface of the workpiece and a reactive force is providedby thelower arm 13, through the die 17, the workpiece, the stripper plate 37,a stripping sleeve 38,'the transfer pins 29, the transmitting means 28or 30, and the piston 24 or the pistons 31, 32which is opposed by fluidpressure in the chamber 23. However, as the chamber 23 decreases in sizewith the relative downward movement ofthe ram with respect to thearrested pistons, energy is stored by means ofsuch fluid, and as soon asthe punch tip 36 breaks through the workpiece and the stroke of the ramreversed, the pressure in such chamber 35 continues to act through theappropriate pistons 24, 31, 32 and the transfer pins 29 to hold thestripper plate 37 against the workpiece until the transmitting means 28or 30 again reengages the upper side of the ram plate 26.

Although various minor modifications might be suggested or made by thoseversed in the art, it should be understood that I wish to embody withinthe scope of the patent warranted hereon, all such embodiments asreasonably and properly come within the scope of the appended claims.

Iclaim: v l. A punch press comprising in combination: I

a. a frame having spaced arms with a reciprocable ram disposed at theupper arm;

b. vertically stationary means for being carried by said frame forreciprocably guiding punch and stripping means;

. means for supporting die means on said lower arm in position to coatwith the punching means;

d. at least a pair of independently movable fluid pressure biasedpistons slidably disposed in said ram; and

e. at least a pair of independently movable means respec tively coatingwith said pair of pistons for transmitting a stripping force from atleast one of said pistons to said stripper means.

2. A punch press according to claim 1 wherein one of said pistons isannular and at least one other of said pistons is disposed within saidone piston.

3. A punch press according to claim 2 wherein said pistons are spacedfrom each other for alternatively coating with punch and stripper meansof differing size.

4. A punch press according tol claim 1 wherein one of said pistons has asomewhat larger working area than the other,

said pistons being connected to a common source of fluid pressure.

5. A punch press according to claim 1 in which one of said pistons isannular and two other of said pistons are disposed Within said onepiston.

6. A punch press according to claim 2, including a ram plate secured tosaid arm and disposed at the low-pressure side of said pistons, and aseries of said transmitting means trapped in and extending substantiallythrough said ram plate near the outer periphery of said annular piston.

7. A punch press according to claim 6, including a further number ofsaid transmitting means trapped in and extending substantially throughsaid ram plate in alignment with the other of said pistons.

8. A punch press according to claim 1, in which said movable means areso shaped as to be retained within said ram in the absence of the punchand stripper means.

9. A punch press according to claim 1, in which said movable means havea length in the direction of ram travel which corresponds to the minimumspacing between said pistons and the punch and stripper means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, a D dMarch 2,

Inventor(s) James J- PaHCOOK It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. 1, line 40, change "thickness" to --thicknesses--;

Col. 1, line 41, change "size" to --sizes--;

C01. 3, line 9, change "coat to --coact--;

C01. 3, line 13, change "coating" to --coac'ting-..;

C01. 3, line 20, change "coating" to --coacting--;

Signed and sealed this 23rd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTI'SCHALK Attesting Officer ActingCommissioner oi Pat

1. A punch press comprising in combination: a. a frame having spacedarms with a reciprocable ram disposed at the upper arm; b. verticallystationary means for being carried by said frame for reciprocablyguiding punch and stripping means; c. means for supporting die means onsaid lower arm in position to coat with the punching means; d. at leasta pair of independently movable fluid pressure biased pistons slidablydisposed in said ram; and e. at least a pair of independently movablemeans respectively coating with said pair of pistons for transmitting astripping force from at least one of said pistons to said strippermeans.
 2. A punch press according to claim 1 wherein one of said pistonsis annular and at least one other of said pistons is disposed withinsaid one piston.
 3. A punch press according to claim 2 wherein saidpistons are spaced from each other for alternatively coating with punchand stripper means of differing size.
 4. A punch press according toclaim 1 wherein one of said pistons has a somewhat larger working areathan the other, said pistons being connected to a common source of fluidpressure.
 5. A punch press according to claim 1 in which one of saidpistons is annular and two other of said pistons are disposed withinsaid one piston.
 6. A punch press according to claim 2, including a ramplate secured to said arm and disposed at the low-pressure side of saidpistons, and a series of said transmitting means trapped in andextending substantially through said ram plate near the outer peripheryof said annular piston.
 7. A punch press according to claim 6, includinga further number of said transmitting means trapped in and extendingsubstantially through said ram plate in alignment with the other of saidpistons.
 8. A punch press according to claim 1, in which said movablemeans are so shaped as to be retained within said ram in the absence ofthe punch and stripper means.
 9. A punch press according to claim 1, inwhich said movable means have a length in the direction of ram travelwhich corresponds to the minimum spacing between said pistons and thepunch and stripper means.